Comparison Study On The Physical Properties And The Disinfection Effect Of The Gypsum Casts After Disinfection

Objective To study the influence of different disinfection methods on the physical properties of gypsum casts and the dinsinfetion effect.Methods Using 4 methods of disinfection:UV exposure,Povidone Iodine spraying,microwave heating,mixing the "84" disinfectant with the gypsum powder.①Make same dimension(50 mm×10 mm×5 mm) gypsum casts,which were disinfected by 4 methods of disinfection.After disinfected,the bending resistance and surface roughness was tested.②Made a metal model which imitating the rigid fixed bridge, testing the dimensional accuracy of the metal model's casts after disinfecting.③Using the type culture strain of Escherichia coli and Staphylococcus aureus to contaminate the gypsum casts,then testing the rate of bacteriostasis after disinfecting.Results①After disinfected by UV exposure and mixed the 84 disinfectant with the gypsum powder,the gypsum casts showed no significant difference on the bending resistance,dimensional accuracy and surface roughness.(P＞0.05).②Compared with the control casts,both types of the casts disinfected by microwave showed a significant difference in the bending resistance test(P＜0.01),and the dimensional accuracy test(P＜0.05).③2.5%Povidone Iodine spraying disinfection adversely affected the bending resistance(P＜0.01).④All of the 4 methods did not adversely affect the surface roughness of the gypsum casts(P＞0.05).⑤After disinfecting,the rate of bacteriostasis was 100%.Conclusion①After disinfected by UV exposure and mixed the "84" disinfectant with the gypsum powder,the gypsum casts showed no significant difference on the bending resistance,dimensional accuracy and surface roughness, and the rate of bacteriostasis was 100%,so both of the two methods are consistent with the clinical requirement.②After disinfected by microwave heating and Povidone Iodine spraying,the rate of bacteriostasis was 100%,but the casts showed a significant difference in the bending resistance test and the dimensional accuracy test, so both of the two methods are not fitted for gypsum casts′s dinsinfection.